1. Field
A sealing member, a scroll compressor, and a method for manufacturing a sealing member for a scroll compressor are disclosed herein.
2. Background
A scroll compressor is a compressor that utilizes a fixed scroll having a spiral wrap and an orbiting scroll revolved with respect to the fixed scroll. That is, a scroll compressor is a compressor in which the fixed scroll and the orbiting scroll are engaged with each other to revolve, thereby reducing a volume of a compression chamber, which is formed between the fixed scroll and the orbiting scroll according to an orbiting motion of the orbiting scroll, and thus, increasing in pressure and discharging a fluid through a discharge hole formed in a central portion of the fixed scroll.
Such a scroll compressor has a feature in which suction, compression, and discharge of a fluid are successively performed while the orbiting scroll revolves. Accordingly, a discharge valve and suction valve may be unnecessary in principle. Further, as a number of components forming the scroll compressor is less in comparison to other types of compressors, the scroll compressor may be simplified in structure and rotate at a high speed in comparison to other types of compressors. Furthermore, as a variation in torque required for compression is less, and suction and compression successively occur, a relatively small amount of noise and vibration may occur.
One important issue in scroll compressors is leakage and lubrication between the fixing scroll and the orbiting scroll. That is, to prevent a refrigerant from leaking between the fixed scroll and the orbiting scroll, an end of a wrap has to be closely attached to a surface of a head plate to prevent the compressed refrigerant from leaking. The head plate may refer to a portion that corresponds to a main body of the fixed scroll or the orbiting scroll. That is, the head plate of the fixed scroll may be closely attached to a wrap of the orbiting scroll, and a head plate of the orbiting scroll may be closely attached to a wrap of the fixed scroll.
On the other hand, friction resistance has to be minimized so as to allow the orbiting scroll to smoothly revolve with respect to the fixed scroll. However, the leakage may conflict with lubrication. That is, when the end of the wrap and the surface of the head plate are strongly attached to each other, it may be advantageous with respect to leakage, but friction may increase, increasing damage due to noise and abrasion. On the other hand, when an adhesion strength is low, the friction may be reduced, but a sealing force may decrease, increasing leakage.
Thus, according to the related art, a back pressure chamber having an intermediate pressure defined as a pressure between a discharge pressure and a suction pressure may be formed in a back surface of the orbiting scroll or the fixed scroll to solve limitations with respect to sealing and friction reduction. That is, the back pressure chamber, which communicates with a compression chamber having an intermediate pressure of a plurality of compression chambers formed between the orbiting scroll and the fixed scroll, may be formed to allow the orbiting scroll and the fixed scroll to be adequately attached to each other, thereby solving the limitations with respect to leakage and lubrication.
The back pressure chamber may be formed on a bottom surface of the orbiting scroll or a top surface of the fixed scroll. For convenience of description, the back pressure chamber formed on the bottom surface of the orbiting scroll and the back pressure chamber formed on the top surface of the fixed scroll may be referred to as a lower back pressure type scroll compressor and an upper back pressure type scroll compressor, respectively. The lower back pressure type scroll compressor has advantages in that the lower back pressure type scroll compressor has a simple structure, and a bypass hole is easily formed. However, as the back pressure chamber is formed on the bottom surface of the orbiting scroll that performs the orbiting motion, the back pressure chamber may change in configuration and position according to the orbiting motion. As a result, the orbiting scroll may be tilted, causing vibration and noise. In addition, an O-ring provided to prevent the refrigerant from leaking may be quickly worn out. The upper back pressure type scroll compressor has a relatively complicated structure. However, as the back pressure chamber is fixed in configuration and position, the fixed scroll may not be tilted, and sealing of the back pressure chamber may be good.
An example of the upper back pressure type scroll compressor is disclosed in Korean Patent Application No. 10-2000-0037517 (hereinafter “related art”), entitled “Method for Processing Bearing Housing and Scroll Machine having Bearing Housing”, whish is hereby incorporated by reference. FIG. 1 is a view illustrating a sealing member provided outside of a back pressure chamber provided in a scroll compressor according to the related art. FIG. 2 is a cross-sectional view taken along line II-II′ of FIG. 1. FIGS. 3A and 3B are simulation views illustrating a sealing process when the sealing member is installed on the scroll compressor according to the related art.
Referring to FIGS. 1 to 3B, in an upper back pressure type scroll compressor according to the related art a sealing member 1 provided between a surface of a back pressure plate 5 and a surface of a floating plate 6 to seal a back pressure chamber is provided. The sealing member 1 may have an approximately annular shape.
The sealing member 1 includes a sealing body 2 having a circular cross-section and a protrusion 3 that protrudes from an outer circumferential surface of the sealing body 2. The protrusion 3 may have a shape that protrudes by a predetermined height from each of inner and outer circumferential surfaces of the sealing body 2. The protrusion 3 may refer to a parting line that occurs when the sealing member 1 is manufactured, for example, a mold is separated in an injection molding process.
FIG. 3A illustrates distribution of pressure applied to the sealing member 1 in a state in which the scroll compressor according to the related art is stopped, and FIG. 3B illustrates distribution of pressure applied to the sealing member 1 in a state in which the scroll compressor according to the related art operates. According to colors, a pressure applied to corresponding portions nay gradually increases in order of blue, green, yellow, orange, and red colors.
When the sealing member 1 is installed in the scroll compressor, a portion on which the protrusion 3 is provided may serve as a sealing surface 4. In this state, when the scroll compressor is driven, the sealing surface changes in position while the floating plate 6 moves upward.
More particularly, a pressure may be applied in an upward direction to the sealing member 1. Thus, the protrusion 3 provided on the inner circumferential surface of the sealing member 1 may move in the upward direction in a state in which the protrusion 3 is closely attached to the floating plate 6. That is, while the scroll compressor is stopped or driven, the protrusion 3 may serve as the sealing surface 4 of the sealing member 1.
As a result, an area to be sealed between the sealing member 1 and the floating plate 6 may be reduced by the protrusion 3, causing leakage of a refrigerant within the back pressure chamber. Also, the protrusion 3 may have a relatively weaker strength than the sealing body 2, and thus, may be easily torn. In addition, when the sealing member 1 is manufactured, the protrusion 3 may have a non-uniform height. Therefore, a sealing effect of the sealing member 1 may be reduced.
As seen by the colors of FIGS. 3A and 3B, as stress is applied to the sealing member 1 through the protrusion 3 having a relatively small area, an intensity of the stress may increase. Thus, a possibility of damage of the sealing member 1 due to fatigue of the sealing member 1 may increase.